1. Field Of The Invention
This invention relates to a keyless chuck, such as a drill chuck, having jaws for holding various tools.
2. Description Of The Prior Art
One type of conventional drill chuck, such as that shown in FIG. 20 and 21, has jaws for holding a tool that are opened or closed by the rotary operation of a chuck key. That is, as shown in FIG. 20, a chuck key 1 is rotatably and detachably inserted into a key hole 2a formed in a body 2. If the chuck key 1 is rotated in the direction indicated by the arrow (a) in FIG. 21, a sleeve 4 which is rotatably mounted on the body 2 is rotated clockwise (b) by a bevel gear 3 engaged with a gear 5 formed on the sleeve 4. A nut (6) which is press-fitted into and fixed to the sleeve 4 is thereby rotated in one direction. Three oblique holes 7 are formed in the body 2 to be arranged in the peripheral direction thereof, a jaw 8 is slidably accommodated in each oblique hole in the longitudinal direction thereof, and an external thread 9 formed on each jaw 8 is meshed with the nut 6, enabling the three jaws 8 to advance and fasten a tool by the rotation of the nut 6 effected in the above-described manner. If the chuck key 1 is rotated in the opposite direction, the nut 6 rotates counterclockwise so that the jaws 8 retreat and release the tool.
This type of conventional device is disadvantageous in terms of operability because the chuck key 1 must be fitted into the key hole 2a formed in the body 2 and it must thereafter be rotated by manual operation. Another problem relates to inconvenience in terms of the maintenance of the device since the chuck key 1 is provided separately from the body and it tends to become lost. If it is lost, the drill chuck cannot be used.